The invention relates to a variable pitch propeller for watercraft, which is mounted in rotary manner in an outboard-supported, pivotable support body and is driven by an engine via a drive connection, its propeller blades being mounted in rotary manner in a propeller hub fixed to the end of the drive connection of a drive shaft and can be set by an adjusting means with different pitch angles.
Variable pitch propellers have long been known as drive means for watercraft. They substantially comprise propeller blades rotatably mounted in a propeller hub and on which the propeller blade pitch can be set. Normally for small drive powers there are two propeller blades and for higher drive powers three, four or more propeller blades. The different constructions of the variable pitch propellers, apart from the number of propeller blades, consequently only differ through the nature of the adjusting means for the propeller blade pitch setting.
The adjusting means for the variable pitch propellers in the case of higher drive or input powers comprise hydrostatic thrust piston drives, which are housed in the interior of drive shaft and the propeller hub. In the case of smaller drive powers mechanical adjusting means are used, in which the propeller blades are adjusted by thrust rods, which act eccentrically on the root or foot of the propeller blade. The actual thrust rods are moved backwards and forwards in the direction of the propeller hub axis via a mechanical linkage. The adjusting force can be applied either manually or by a linear motor.
These adjusting means have proved satisfactory in numerous use cases. However, they suffer from the disadvantage of being complicated to constructions, which are correspondingly expensive. As a result the variable pitch propeller has only been adopted in specific categories of watercraft, because even in the case of the simplest construction the price for certain watercraft categories is still too high.